Superconducting, Ferromagnetic and Antiferromagnetic Phases in the t-t^′ Hubbard Model

Abstract

We apply a renormalization group approach to the determination of the phase diagram of the t-t^′ Hubbard model at the Van Hove filling, as function of t^′ / t, for small values of U / t.The model presents ferromagnetic, antiferromagnetic and d-wavesuperconducting phases. Antiferromagnetism and d-wavesuperconductivity arise from the same interactions, and competein the same region of parameter space.